对于在单个语句中多次出现的替换变量,如何只对SQL Developer/SQL +提示一次？

DECLARE
  v_name employees.last_name%TYPE := '&last_name';
BEGIN
  FOR emp_rec IN (SELECT * FROM employees WHERE last_name = v_name)
  LOOP
    DBMS_OUTPUT.PUT_LINE(emp_rec.first_name || ' ' || emp_rec.last_name);
  END LOOP;
END;

DECLARE
  CURSOR c_employees IS
    SELECT * FROM employees WHERE last_name = '&last_name';
BEGIN
  FOR emp_rec IN c_employees
  LOOP
    DBMS_OUTPUT.PUT_LINE(emp_rec.first_name || ' ' || emp_rec.last_name);
  END LOOP;
END;